stream_select

Runs the equivalent of the select() system call on the given arrays of streams with a timeout specified by seconds and microseconds.

stream_select Function synopsis

stream_select(
    ?array &$read,
    ?array &$write,
    ?array &$except,
    ?int $seconds,
    ?int $microseconds = null,
    $context = null
  ): int|false

Parameters

$read

Passed by referenceType?array

The streams listed in the $read array will be watched to see if characters become available for reading (more precisely, to see if a read will not block - in particular, a stream resource is also ready on end-of-file, in which case an fread will return a zero length string).

$write

Passed by referenceType?array

The streams listed in the $write array will be watched to see if a write will not block.

$except

Passed by referenceType?array

The streams listed in the $except array will be watched for high priority exceptional ("out-of-band") data arriving.

$seconds

Type?int

The $seconds and $microseconds together form the timeout parameter, $seconds specifies the number of seconds while $microseconds the number of microseconds. The $timeout is an upper bound on the amount of time that stream_select will wait before it returns. If $seconds is set to 0 and $microseconds is 0 or null, stream_select will not wait for data - instead it will return immediately, indicating the current status of the streams.

$microseconds

OptionalType?intDefault valuenull

See $seconds description.

$context

OptionalDefault valuenull

Note that the parameters $read, $write, and $except are passed by reference, and contain additional/updated context data that may be useful.

Return value

Typeint|false

On success stream_select returns the number of stream resources contained in the modified arrays, which may be zero if the timeout expires before anything interesting happens. On error false is returned and a warning raised (this can happen if the system call is interrupted by an incoming signal).